Viewing archive of Thursday, 21 September 2017

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2017 Sep 21 1239 UTC

SIDC Forecast

Solar flares

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Sep 2017	076	006
22 Sep 2017	076	007
23 Sep 2017	079	016

Bulletin

Over the past 24 hours the solar activity was very low with only a few B-class flares recorded. The major flare was a B8.4-class flare at 19:32 UT attributed to the Catania sunspot group 55 (NOAA active region 2680). The returning region has been assigned a new number: Catania sunspot group 56 (NOAA active region 2681). Both regions show a simple photospheric magnetic field configuration (alpha) and are unlikely to produce any strong flaring activity. We expect the solar activity to remain low with some B-class flares and a slight chance for C-class flares.

No Earth directed CMEs have been observed and the solar protons remained at background level over the past 24 hours.

The Earth is currently inside a slow solar wind flow that has declined further from 500 to 400 Km/s. The interplanetary magnetic field magnitude remained below 6 nT and the Bz component fluctuated between -4 and 4 nT being mainly negative. A relatively small equatorial coronal hole in the south hemisphere has crossed the central meridian yesterday Sept 20 around 16:30 UT. The associated fast solar wind is expected to arrive at Earth on Sept 23 late afternoon.

Geomagnetic conditions were quiet to unsettled with Kp (NOAA) and local K (Dourbes) indexes ranging between 1-3 and 0-2 respectively. The geomagnetic conditions are expected to remain quiet to unsettled until Sept 23 when the fast solar will reach Earth.

Today's estimated international sunspot number (ISN): 023, based on 22 stations.

Solar indices for 20 Sep 2017

Wolf number Catania	012
10cm solar flux	074
AK Chambon La Forêt	012
AK Wingst	012
Estimated Ap	012
Estimated international sunspot number	021 - Based on 28 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

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